Means for producing ingots



Patented Aug. 3, 1937 UNITED STATES PATENT or-FicE 2,088,696 MEANS ronraonUcxNG TNco'rs Application June 21, 1934, Serial No. '131,780

4 Claims. (Cl. 22-139)l This invention relates to methods of and meansfor producing ingots and more particularly to methods of and means foreffecting localized accelerated cooling of a particular portion of the 5ingot metal whereby a more homogeneous ingot is produced, and wherebysetting up of the mold assembly and stripping of the ingot isfacilitated.

Practically all ingots made in the commercial production of steel arecast in vertical molds, i. e.,

l molds having vertically extending matricesor ingot-forming chambers.Such molds may be classified into two broad categories, namely,bigend-down molds, in which the matrix is larger at the bottom than atthe top thereof, and big-end- 15 up molds in which the matrix is largerat the top. The bottom end portions of ingots cast in either big-end-upor big-end-down molds have a crystalline structure usually somewhatdifferent from that of the intermediate and upper portions of the 20ingot, due to the intersection of the lines of growth of the dendriticcrystals from the bottom and lower side walls of thev mold. Thiscrystal-A line structure results in the formation of cleavage planes,which frequently causelines of weakness 25 within the lower part of theingot when it is rolled in the mill, necessitating cutting off orcropping of a considerable portion of the rolled billet or bloom inwhich these lines of weaknesses occur. The formation of the undesirablecleavage 30 planes which result in lines of weakness is much morepronounced in big-end-down ingots than in ingots of the big-end-up type.

One object of our invention is to reduce as nearly as possible theformation of these lines 35 of weakness by eliminating or reducing theunderlying cause, i. e., by reducing to a minimum the relative dendriticgrowth in a horizontal direction that causes the formation of cleavageplanes at the junction of the horizontaldendrites with 4o the verticallyextending dendrites, this being accomplished in accordance with theinvention by cooling different portions of the bottom of the ingot atdifferent ratesor times.

Another object is to provide an improved in/gotA 45 mold or assemblyconstructed or equipped to effect differential cooling of an ingot inaccordance with our improved method.

A further object of the invention is to provide an improved assembly ofbig-end-up mold 50 and bottom cooling element therefor, such as a plughaving a high coefficient of heat conductivity compared to that of themold proper, the arrangement being such that the mold can be lowered onto a support on which the cooling 55 element has previously beenpositioned and/or secured, and the cooling element thereby extendedrelatively into the mold bottom opening. In accordance with a furtherfeature of 'the invention,

a relatively thin metallic sealing plate is located Within the bottomportion of the mold in heattransferring relation to the cooling element,and preferably is seated on and supported by the mold bottom walls andthe cooling element. Other objects will become apparent from a readingof the following description, the appended claims, and the accompanyingdrawing, in which:

Figure 1 is a vertical sectional view of a Gathmann mold, coolingelement, and sealing plate assembly arranged in accordance with onefeature of the invention and being one form adapted for use inpractising our improved method of ingot production; v

Figure 2 is a horizontal sectional view taken on the line 2-2 of Figure1; and

'Figure 3 is a fragmentary'vertical sectional 20 view of a modified formof mold', cooling element, and sealing plate assembly.

Our improved method can be practised by' the use of 'various molds ormold assemblies ,constructed and/or arranged in accordance with theinvention, but for the purpose of illustration and simplicity ofdisclosure -will be describedA4 as practised in the production ofbig-end-up ingots. It will be understood, however, that ingots can bemade in accordance with the invention in mold assemblies which maydiffer in some respects from those shown and described herein.

The mold assembly shown in Figure 1 comprises a big-end-up Gathmann moldM of the general type disclosed in United States Patent 1,419,454, ofJune .13, 1922,` andv preferably is made of cast iron. The mold isprovided with a bottom openingM1 which ilares outwardly at its lower endportion as at M1, and may be positioned l on anysuitable support, as forexample, a plat- 40 form S carried by a transfer car C The opening M1 isaligned with an opening S1 in the supports through which a stripper rodR is adapted to pass.

In accordance with our invention a cooling element having a highcoeiiicient' of heat conductivity, in the form shown a copper plug P, ispositioned within the opening M1 in the mold, the lower end of the plugbeing of reduced diameter and extending downwardly into the opening S1in the support S, the annular shoulder P1 intervening between the upperandilower portions of the plug seating uponthe support S rfor holdingthe plug in the position shown. A thin 'metallic sealing plate p, whichymaybe of low 55 formed of cast iron,

or other material carbon steel, is positioned at the bottom of the moldchamber, resting upon the bottom Walls of the latter and preferablybeing partially supported by, and at least being in heat-transferringrelation to the plug P. The purpose of the plate p is to act as aprimary closure for preventing the egress of molten metal from the moldbottom and also for preventing the stream of molten metal entering themold from impacting directly upon the plug P. To facilitate centering ofthe plate p with respect to the plug P, the plate preferably is providedwith a pin p1 adapted to extend into a hole P2 located centrally in thetop of the plug. This preferred arrangement is described in more detailin Patent 1,419,454, of June 13, 1922, issued to Emil Gathmann, one ofthe joint inventors of the methods of and means for producing ingots.disclosed and claimed herein.

The chamber of the mold M is formed with a necked-in bottom end portionM3 which substantially merges with the top of the cooling plug P; thebottom of the necked-in portion and the top of the plug togetherdefining the bottom seat or bottom wall of the mold M on which thesealing plate is positioned.

In accordance with our improved method, the central portion of thebottom of the ingot is chilled much more rapidly than the surroundingbottom portion, and to this end the cooling plug P, whose upper surfaceforms the central portion of the mold bottom wall, is formed of amaterial having a coefficient of heat conductivity considerably higherthan that of the cast iron forming the surrounding mold bottom portionM3. When the mold proper is as is usually the case, or a material havinga coefficient of heat conductivity comparable to to form the coolingsubstantially pure of heat conductivity of pure copper is approximatelyeight times that of cast iron. If it is desired to employ a copperalloy, care should be exercised in the selection of the alloy, and, inany case, the material used for the plug should have a coefficient ofheat transfer considerably greater than that of the material of the moldproper. The cooling plug P should be massive and preferably should be ofa diameter at least approximately one-half the minimum width of the moldchamber above the necked-in portion M3, and the depth of the plug shouldbe at least one-fourth as great as its diameter, these relativedimensions having been found to effect the differential cooling ratesproducing the best results. 'I'he term diameter is not to be taken in alimiting sense, since the plug need not necessarily be round incross-section.

In practising our method plug P of copper, preferably tively quiet poolof molten metal in contact with the plug and the. surrounding bottomportion M3, which is the condition most conducive to obtainment of bestresults from the cooling of the central and surrounding bottom portionsof the ingot at different rates. After the aforesaid pool that of castiron, We prefer copper, since the coefficient` until the pouring iscompleted. The high heat absorbing properties of the plug P result inthe ingot metals being cooled much more rapidly at the central portionof its bottom end than at the surrounding bottom portion, and We havefound that this differential cooling reduces and practically eliminatesthe formation of the damaging cleavage planes hereinbefore referred to.The plate p protects the plug P from direct impact of the enteringstream of molten metal, but, being thin, the plate does not interfereappreciably with the cooling action of the plug.

By employing a sealing plate made of a material having a high meltingcoeiiicient and a cooling plug made of a material having a highcoeiiicient of heat conductivity, it is possible to seal the mold bottomeiectively without the cooling plugs fitting tightly or even snugly inthe mold bottom opening; in fact, a considerable clearance space M4 maybe' left between the cooling plug and the walls of the mold bottomopeningwithout there being danger of molten metal passing between thevertical Walls of the mold bottom opening and the vertical Walls of thecooling plug, should there at any time be a slight leakage around theedges of the sealing plate. The ingot metal lying in the bottom of thepool immediately over the sealing plate is chilled so rapidly that evenshould there be a slight leakage between the sealing plate and thecooling plug the ingot metal Will solidify before it can enter theclearance space M4 to any appreciable extent. This chilling by thecooling plug having a high coeilicient of heat transfer is so rapid thatthe size of the clearance space, which practical experience inpracticing an invention has been demonstrated may safely be left, ismuch greater than would be expected. For example, in a. case of moldshaving a minimum chamber width o1' about twenty inches and having a,bottom opening of about 12" diameter, a clearance space o1' as much asone-eighth inch around the plug may be used with no danger of run-outsor the formation of fins which would result in sticking plugs or ingots.The cooling plug, having a high coeflicient of heat conductivity, hasthe capacity to extract heat from the lower surface of the plate p morerapidly than the heat of the molten ingot metal can pass into the plate,so that the plate p will be prevented from reaching a temperature highenough to cause it to stick to the mold bottom.

Because of the large clearance space M4 thus made permissible, andfurther because o1' the tapered or flared opening M2 in the mold bottom,assembly of the mold and cooling plug on a support preparatory toplacing the sealing .plate on top cf the cooling plug is greatlyfacilitated, and there is no difculty in bringing the mold bottomopening l into substantial registration with the plug during lowering ofthe mold. vIn

lower end possesses the disadvantage of requlring that the closure plugbe introduced into the top end of the mold by meansof the use of tongsor like implements, and, /a cooling plug being quite heavy, weighing atleast a hundred to two hundred pounds, this usually necessitates a craneoperation. Molds having tapered bottom openings, smallest at their topends, while permitting the mold to be lowered over the plug, do notpermit a, stripping instrumentality to be moved upward through thebottom of the mold. AWe believe our improved assembly is the rstpractical arrangement possessing vboth of the advantages of permittingthe mold to be lowered over the plug Without exact centering andpermitting the plug to be moved upwardly through the mold bottom duringstripping.

In the embodiment shown in Figure 3 the cooling Aplug is made integralwith the support or platform upon which the mold rests. While thisarrangement does not provide for stripping of the ingot by means o thecooling plug, as is possible with the construction shown in Figure 1, itnevertheless has some advantages for practising our improved methodsinasmuch as the volume of the cooling plug is greatly enlarged by thecontinuous heat transferring character of the unitary plug and moldplatform.

The method described above and the apparatus disclosed are the mode ofprocedure and embodiment of construction preferred atthis time, butvarious changes may be made without departing from the invention asdencd in the claims.

We claim:

l. An ingot mold assembly comprising a bigend-up ingot mold having abottom opening and a cooling plug in said opening, said cooling plugbeing substantially flush with the lower part of the horizontal moldmatrix and being made of material having a coeicient of heatconductivity at least several times that of the body of the mold, incombination with a. sealing plate superimposed above said cooling plug,said sealing plate being constructed of a material having a highermelting point than the material comprising said cooling plug.

2. An ingot mold assembly comprising a bigend-up ingot mold having abottom opening and a cooling plug in said opening, said cooling plugbeing substantially ush with the lower part of the horizontal moldmatrix and being made of material having a coeicient of heatconductivity at least several times that of the body of the mold, incombination With a sealing plate superimposed above said cooling plug,said sealing plate being constructed of a material having a highermelting point than the material comprising said cooling plug, and meansfor centering said sealing plate with respect to the vertical axis ofthe cooling plug.

3. An ingot mold assembly comprising a bigend-up cast ironingot moldhaving a bottom opening; a heavy copper plug in said opening; and a thinplate of ferrous material in said mold above and in heat-transferringrelation to said plug.

4. An ingot mold assembly comprising a cast iron mold having a bottomopening; a closure for said bottom opening consisting of a massive bodyof relatively thick copper material and a relatively thin sealing plateof ferrous sheet material superimposed and in heat-conducting relationto said copper material.

EMIL GA'IHMANN.

HARRY S. BRADLEY.

